Full plate armour made the wearer virtually impervious to sword blows as well as providing significant protection against arrows, bludgeons and even early firearms. Sword edges could not penetrate even relatively thin plate (as little as 1 mm). Also, although arrows shot from bows, crossbows and early firearms could occasionally pierce plate especially at close range, later improvements in the steel forging techniques and armour design made even this line of attack increasingly difficult. By its apex, hardened steel plate was almost impregnable on the battlefield. Knights were instead increasingly felled by polearms such as the halberd and blunt weapons such as maces or war hammers that could send concussive force through the plate armour resulting in injuries such as broken bones, organ haemorrhage and/or head trauma. Another tactic was to attempt to strike through the gaps between the armour pieces, using daggers, spears and spear points to attack the man-at-arms' eyes or joints.
Contrary to common misconceptions, a well-made suit of medieval 'battle' armour (as opposed to the primarily ceremonial 'parade' and 'tournament' armour popular with kings and nobility of later years) hindered its wearer no more than the equipment carried by soldiers today. It should be remembered that an armoured knight would be trained to wear armour from his teens, and would likely develop the technique and endurance needed to comfortably run, crawl, climb ladders, as well as mount and dismount his horse without recourse to a crane
